The invention relates to engines adapted to the conversion of solar thermal energy to mechanical and electrical energy and in particular to improvements in differential temperature engines previously described by the author in U.S.A. Pat. Nos. 3,841,097 and 3,846,984.
Solar energy is available in practically unlimited quantities, it is free, and continuously renewable. Despite its potential, solar energy has not served as a significal source of mechanical and electric energy. This has been caused by the high capital investment and amortization rates of components of the systems required for the conversion of solar thermal energy to mechanical and electric energy. This has reduced the ability of solar energy to compete with alternate energy source such as conventional fuels.
Differential temperature engines are ideally suited for the solar conversion systems because of their sensitivity and relatively efficient operations at low temperatures. Essentially a differential temperature engine consists of a relatively warm and a relatively cold chamber containing a low boiling point fluid. Alternate opening and closing of a communication between the vapor phases of the warm and cold chambers results in changes in vapor pressure in the chambers. The vapor pressure changes are translated to useful work through a moving member which responds to changes in the vapor pressure. The differential temperature engine, like most heat engines, requires a regulated valve system between the high pressure and low pressure portions of the engine. This constitutes a relatively expensive component of the engine. The present invention consists of a differential temperature engine which operates without a valve system or with minimal number of valves. In addition the engine operates through a float without close fitting moving components, a fact which greatly reduces wear and tear due to friction.
Another unique feature of the valveless differential temperature engine is the fact that it can utilize flat plate collector systems and storage tanks of the type available in standard solar hot water systems. Thus, a roof solar hot water system can be utilized not only for heating a home water supply but also for activation of air conditioner compressors and generation of electric power.